<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8"/>
        <title>01test</title>
        <script src="js/jquery-1.12.4.min.js"></script>
    </head>
    <body>
        <div id="box">this is a div</div>
    </body>
    <script>
        $( function () {                          //jq中相当于函数名加括号进行函数调用，然后传参
            $('#box').click( function () {        //把函数写到括号中，相当于参数
                alert( $(this).html() );
            } )
        } )
    </script>
</html>